WikiExporter.php

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<?php
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\MediaWikiServices;
use MediaWiki\Revision\RevisionRecord;
use MediaWiki\Revision\RevisionStore;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\IResultWrapper;
 
class WikiExporter {
    public $list_authors = false;
 
    public $dumpUploads = false;
 
    public $dumpUploadFileContents = false;
 
    public $author_list = "";
 
    public const FULL = 1;
    public const CURRENT = 2;
    public const STABLE = 4; // extension defined
    public const LOGS = 8;
    public const RANGE = 16;
 
    public const TEXT = XmlDumpWriter::WRITE_CONTENT;
    public const STUB = XmlDumpWriter::WRITE_STUB;
 
    protected const BATCH_SIZE = 50000;
 
    public $text;
 
    public $sink;
 
    private $writer;
 
    protected $db;
 
    protected $history;
 
    protected $limitNamespaces;
 
    private $revisionStore;
 
    private $hookRunner;
 
    public static function schemaVersion() {
        global $wgXmlDumpSchemaVersion;
        return $wgXmlDumpSchemaVersion;
    }
 
    public function __construct(
        $db,
        $history = self::CURRENT,
        $text = self::TEXT,
        $limitNamespaces = null
    ) {
        $this->db = $db;
        $this->history = $history;
        $this->writer = new XmlDumpWriter( $text, self::schemaVersion() );
        $this->sink = new DumpOutput();
        $this->text = $text;
        $this->limitNamespaces = $limitNamespaces;
        $services = MediaWikiServices::getInstance();
        $this->hookRunner = new HookRunner( $services->getHookContainer() );
        $this->revisionStore = $services->getRevisionStore();
    }
 
    public function setSchemaVersion( $schemaVersion ) {
        $this->writer = new XmlDumpWriter( $this->text, $schemaVersion );
    }
 
    public function setOutputSink( &$sink ) {
        $this->sink =& $sink;
    }
 
    public function openStream() {
        $output = $this->writer->openStream();
        $this->sink->writeOpenStream( $output );
    }
 
    public function closeStream() {
        $output = $this->writer->closeStream();
        $this->sink->writeCloseStream( $output );
    }
 
    public function allPages() {
        $this->dumpFrom( '' );
    }
 
    public function pagesByRange( $start, $end, $orderRevs ) {
        if ( $orderRevs ) {
            $condition = 'rev_page >= ' . intval( $start );
            if ( $end ) {
                $condition .= ' AND rev_page < ' . intval( $end );
            }
        } else {
            $condition = 'page_id >= ' . intval( $start );
            if ( $end ) {
                $condition .= ' AND page_id < ' . intval( $end );
            }
        }
        $this->dumpFrom( $condition, $orderRevs );
    }
 
    public function revsByRange( $start, $end ) {
        $condition = 'rev_id >= ' . intval( $start );
        if ( $end ) {
            $condition .= ' AND rev_id < ' . intval( $end );
        }
        $this->dumpFrom( $condition );
    }
 
    public function pageByTitle( $title ) {
        $this->dumpFrom(
            'page_namespace=' . $title->getNamespace() .
            ' AND page_title=' . $this->db->addQuotes( $title->getDBkey() ) );
    }
 
    public function pageByName( $name ) {
        $title = Title::newFromText( $name );
        if ( $title === null ) {
            throw new MWException( "Can't export invalid title" );
        } else {
            $this->pageByTitle( $title );
        }
    }
 
    public function pagesByName( $names ) {
        foreach ( $names as $name ) {
            $this->pageByName( $name );
        }
    }
 
    public function allLogs() {
        $this->dumpFrom( '' );
    }
 
    public function logsByRange( $start, $end ) {
        $condition = 'log_id >= ' . intval( $start );
        if ( $end ) {
            $condition .= ' AND log_id < ' . intval( $end );
        }
        $this->dumpFrom( $condition );
    }
 
    protected function do_list_authors( $cond ) {
        $this->author_list = "<contributors>";
        // rev_deleted
 
        $revQuery = $this->revisionStore->getQueryInfo( [ 'page' ] );
        $res = $this->db->select(
            $revQuery['tables'],
            [
                'rev_user_text' => $revQuery['fields']['rev_user_text'],
                'rev_user' => $revQuery['fields']['rev_user'],
            ],
            [
                $this->db->bitAnd( 'rev_deleted', RevisionRecord::DELETED_USER ) . ' = 0',
                $cond,
            ],
            __METHOD__,
            [ 'DISTINCT' ],
            $revQuery['joins']
        );
 
        foreach ( $res as $row ) {
            $this->author_list .= "<contributor>" .
                "<username>" .
                htmlspecialchars( $row->rev_user_text ) .
                "</username>" .
                "<id>" .
                ( (int)$row->rev_user ) .
                "</id>" .
                "</contributor>";
        }
        $this->author_list .= "</contributors>";
    }
 
    protected function dumpFrom( $cond = '', $orderRevs = false ) {
        if ( $this->history & self::LOGS ) {
            $this->dumpLogs( $cond );
        } else {
            $this->dumpPages( $cond, $orderRevs );
        }
    }
 
    protected function dumpLogs( $cond ) {
        $where = [];
        # Hide private logs
        $hideLogs = LogEventsList::getExcludeClause( $this->db );
        if ( $hideLogs ) {
            $where[] = $hideLogs;
        }
        # Add on any caller specified conditions
        if ( $cond ) {
            $where[] = $cond;
        }
        $result = null; // Assuring $result is not undefined, if exception occurs early
 
        $commentQuery = CommentStore::getStore()->getJoin( 'log_comment' );
        $actorQuery = ActorMigration::newMigration()->getJoin( 'log_user' );
 
        $tables = array_merge(
            [ 'logging' ], $commentQuery['tables'], $actorQuery['tables'], [ 'user' ]
        );
        $fields = [
            'log_id', 'log_type', 'log_action', 'log_timestamp', 'log_namespace',
            'log_title', 'log_params', 'log_deleted', 'user_name'
        ] + $commentQuery['fields'] + $actorQuery['fields'];
        $options = [
            'ORDER BY' => 'log_id',
            'USE INDEX' => [ 'logging' => 'PRIMARY' ],
            'LIMIT' => self::BATCH_SIZE,
        ];
        $joins = [
            'user' => [ 'JOIN', 'user_id = ' . $actorQuery['fields']['log_user'] ]
        ] + $commentQuery['joins'] + $actorQuery['joins'];
 
        $lastLogId = 0;
        while ( true ) {
            $result = $this->db->select(
                $tables,
                $fields,
                array_merge( $where, [ 'log_id > ' . intval( $lastLogId ) ] ),
                __METHOD__,
                $options,
                $joins
            );
 
            if ( !$result->numRows() ) {
                break;
            }
 
            $lastLogId = $this->outputLogStream( $result );
        }
    }
 
    protected function dumpPages( $cond, $orderRevs ) {
        $revQuery = $this->revisionStore->getQueryInfo( [ 'page' ] );
        $slotQuery = $this->revisionStore->getSlotsQueryInfo( [ 'content' ] );
 
        // We want page primary rather than revision.
        // We also want to join in the slots and content tables.
        // NOTE: This means we may get multiple rows per revision, and more rows
        // than the batch size! Should be ok, since the max number of slots is
        // fixed and low (dozens at worst).
        $tables = array_merge( [ 'page' ], array_diff( $revQuery['tables'], [ 'page' ] ) );
        $tables = array_merge( $tables, array_diff( $slotQuery['tables'], $tables ) );
        $join = $revQuery['joins'] + [
                'revision' => $revQuery['joins']['page'],
                'slots' => [ 'JOIN', [ 'slot_revision_id = rev_id' ] ],
                'content' => [ 'JOIN', [ 'content_id = slot_content_id' ] ],
            ];
        unset( $join['page'] );
 
        $fields = array_merge( $revQuery['fields'], $slotQuery['fields'] );
        $fields[] = 'page_restrictions';
 
        if ( $this->text != self::STUB ) {
            $fields['_load_content'] = '1';
        }
 
        $conds = [];
        if ( $cond !== '' ) {
            $conds[] = $cond;
        }
        $opts = [ 'ORDER BY' => [ 'rev_page ASC', 'rev_id ASC' ] ];
        $opts['USE INDEX'] = [];
 
        $op = '>';
        if ( is_array( $this->history ) ) {
            # Time offset/limit for all pages/history...
            # Set time order
            if ( $this->history['dir'] == 'asc' ) {
                $opts['ORDER BY'] = 'rev_timestamp ASC';
            } else {
                $op = '<';
                $opts['ORDER BY'] = 'rev_timestamp DESC';
            }
            # Set offset
            if ( !empty( $this->history['offset'] ) ) {
                $conds[] = "rev_timestamp $op " .
                    $this->db->addQuotes( $this->db->timestamp( $this->history['offset'] ) );
            }
            # Set query limit
            if ( !empty( $this->history['limit'] ) ) {
                $maxRowCount = intval( $this->history['limit'] );
            }
        } elseif ( $this->history & self::FULL ) {
            # Full history dumps...
            # query optimization for history stub dumps
            if ( $this->text == self::STUB ) {
                $opts[] = 'STRAIGHT_JOIN';
                $opts['USE INDEX']['revision'] = 'rev_page_id';
                unset( $join['revision'] );
                $join['page'] = [ 'JOIN', 'rev_page=page_id' ];
            }
        } elseif ( $this->history & self::CURRENT ) {
            # Latest revision dumps...
            if ( $this->list_authors && $cond != '' ) { // List authors, if so desired
                $this->do_list_authors( $cond );
            }
            $join['revision'] = [ 'JOIN', 'page_id=rev_page AND page_latest=rev_id' ];
            $opts[ 'ORDER BY' ] = [ 'page_id ASC' ];
        } elseif ( $this->history & self::STABLE ) {
            # "Stable" revision dumps...
            # Default JOIN, to be overridden...
            $join['revision'] = [ 'JOIN', 'page_id=rev_page AND page_latest=rev_id' ];
            # One, and only one hook should set this, and return false
            if ( $this->hookRunner->onWikiExporter__dumpStableQuery( $tables, $opts, $join ) ) {
                throw new MWException( __METHOD__ . " given invalid history dump type." );
            }
        } elseif ( $this->history & self::RANGE ) {
            # Dump of revisions within a specified range.  Condition already set in revsByRange().
        } else {
            # Unknown history specification parameter?
            throw new MWException( __METHOD__ . " given invalid history dump type." );
        }
 
        $result = null; // Assuring $result is not undefined, if exception occurs early
        $done = false;
        $lastRow = null;
        $revPage = 0;
        $revId = 0;
        $rowCount = 0;
 
        $opts['LIMIT'] = self::BATCH_SIZE;
 
        $this->hookRunner->onModifyExportQuery(
            $this->db, $tables, $cond, $opts, $join, $conds );
 
        while ( !$done ) {
            // If necessary, impose the overall maximum and stop looping after this iteration.
            if ( !empty( $maxRowCount ) && $rowCount + self::BATCH_SIZE > $maxRowCount ) {
                $opts['LIMIT'] = $maxRowCount - $rowCount;
                $done = true;
            }
 
            $queryConds = $conds;
            $queryConds[] = 'rev_page>' . intval( $revPage ) . ' OR (rev_page=' .
                intval( $revPage ) . ' AND rev_id' . $op . intval( $revId ) . ')';
 
            # Do the query and process any results, remembering max ids for the next iteration.
            $result = $this->db->select(
                $tables,
                $fields,
                $queryConds,
                __METHOD__,
                $opts,
                $join
            );
            if ( $result->numRows() > 0 ) {
                $lastRow = $this->outputPageStreamBatch( $result, $lastRow );
                $rowCount += $result->numRows();
                $revPage = $lastRow->rev_page;
                $revId = $lastRow->rev_id;
            } else {
                $done = true;
            }
 
            // If we are finished, close off final page element (if any).
            if ( $done && $lastRow ) {
                $this->finishPageStreamOutput( $lastRow );
            }
        }
    }
 
    protected function outputPageStreamBatch( $results, $lastRow ) {
        $rowCarry = null;
        while ( true ) {
            $slotRows = $this->getSlotRowBatch( $results, $rowCarry );
 
            if ( !$slotRows ) {
                break;
            }
 
            // All revision info is present in all slot rows.
            // Use the first slot row as the revision row.
            $revRow = $slotRows[0];
 
            if ( $this->limitNamespaces &&
                !in_array( $revRow->page_namespace, $this->limitNamespaces ) ) {
                $lastRow = $revRow;
                continue;
            }
 
            if ( $lastRow === null ||
                $lastRow->page_namespace !== $revRow->page_namespace ||
                $lastRow->page_title !== $revRow->page_title ) {
                if ( $lastRow !== null ) {
                    $output = '';
                    if ( $this->dumpUploads ) {
                        $output .= $this->writer->writeUploads( $lastRow, $this->dumpUploadFileContents );
                    }
                    $output .= $this->writer->closePage();
                    $this->sink->writeClosePage( $output );
                }
                $output = $this->writer->openPage( $revRow );
                $this->sink->writeOpenPage( $revRow, $output );
            }
            $output = $this->writer->writeRevision( $revRow, $slotRows );
            $this->sink->writeRevision( $revRow, $output );
            $lastRow = $revRow;
        }
 
        if ( $rowCarry ) {
            throw new LogicException( 'Error while processing a stream of slot rows' );
        }
 
        return $lastRow;
    }
 
    protected function getSlotRowBatch( $results, &$carry = null ) {
        $slotRows = [];
        $prev = null;
 
        if ( $carry ) {
            $slotRows[] = $carry;
            $prev = $carry;
            $carry = null;
        }
 
        while ( $row = $results->fetchObject() ) {
            if ( $prev && $prev->rev_id !== $row->rev_id ) {
                $carry = $row;
                break;
            }
            $slotRows[] = $row;
            $prev = $row;
        }
 
        return $slotRows;
    }
 
    protected function finishPageStreamOutput( $lastRow ) {
        $output = '';
        if ( $this->dumpUploads ) {
            $output .= $this->writer->writeUploads( $lastRow, $this->dumpUploadFileContents );
        }
        $output .= $this->author_list;
        $output .= $this->writer->closePage();
        $this->sink->writeClosePage( $output );
    }
 
    protected function outputLogStream( $resultset ) {
        foreach ( $resultset as $row ) {
            $output = $this->writer->writeLogItem( $row );
            $this->sink->writeLogItem( $row, $output );
        }
        return $row->log_id ?? null;
    }
}